1. Field of the Invention
The present invention relates to a compressor which comprises a cylinder block provided with a plurality of cylinder bores, a plurality of sleeves or liners fixedly fitted in and extending beyond corresponding cylinder bores, and a plurality of pistons reciprocating between a top dead center and a bottom dead center within the sleeves.
2. Description of Related Art
In compressors, when a piston reciprocates in a sleeve in an axial direction, the piston may incline slightly in reaction to the force of a compressed fluid. Such inclination of the piston tends to occur more frequently in a compressor having a swash plate. Such inclination of the piston causes unbalanced wear of the sleeve and damage to the coating of the piston.
In Japanese Patent Application No. JP-A 2001-115955, a compressor is described which takes measures to avoid the inclination of a piston. The compressor described in that application employs a clearance fit structure of a sleeve within a cylinder bore at one or both end portions in order that the sleeve fitted in to the cylinder bore may incline in accordance with the inclination of the piston reciprocating in the sleeve. In that compressor, the cylinder bore and the sleeve have the same length in the axial direction. The cylinder bore comprises three portions: a middle portion and two end portions extending from the middle portion to the respective ends of the cylinder bore. Each of the end portions has an inner diameter that is larger than the inner diameter of the middle portion. The inner diameter of the middle portion is substantially equal to the outer diameter of the sleeve. Thus, there are slight clearances between the sleeve and the end portions of the cylinder bore facing the sleeve. In the structure disclosed in this known compressor, the sleeve also inclines when the piston inclines, so that unbalanced wear of the sleeve and damage of the coating of the piston may be reduced or avoided.
Nevertheless, the formation of the slight clearances employed in this known compressor is an exacting task in view of their dimensions and, therefore, increases manufacturing costs and complexity.